(1) Field of the Invention
The present invention relates to an applicator of a pen (brush) type for application (including writing and drawing) of ink, cosmetics such as manicure and the like and other application liquids, more detailedly relating to a cartridge type applicator having a cylindrical cartridge tank which stores application liquid and can supply the application liquid to the applying portion such as a writing tip or the like.
(2) Description of the Prior Art
As a conventional applicator, there has been a proposal of a cartridge type writing instrument shown in FIGS. 14 and 15 (see, for example, the publication of Japanese Registered Utility Model No. 2602464). This cartridge type applicator is constructed of an applicator body 70, a cartridge tank 80 and a tail plug 90.
Applicator body 70 is made of synthetic resin, having an opening at the rear end and a front barrel 71 integrally formed at the front end, with an annular projected fitting portion (projected engaging portion) 72 formed near the rear end on the inner periphery so as to be perpendicular to the axis. Front barrel 71 is formed with a brush 71a projected forwards. A pipe 73 for supplying the liquid to this brush element 71a is fixed to front barrel 71 and is arranged so as to project rearwards in the front part inside applicator body 70. Designated at 74 is a cap fitted on applicator body 70.
A cartridge tank 80 holds an application liquid inside a tank body 81. A valve element 82 is attached to an opening at the front end of tank body 81 while an inner front barrel 83 of synthetic resin is fitted on the outer periphery at the front end of tank body 81 so as to cover the valve element 82. A stepped portion 84 facing to the rear is formed on the outer periphery of tank body 81.
A tail plug 90 is a hollow cylinder formed of synthetic resin having open ends. A cutout portion 91 is formed in its side at the rear end. A stepped portion 92, against slippage when the tail plug is fitted, is formed in the side at the rear end. An anti-rolling projection 93 is formed on the outer periphery. Tail plug 90 further has a depressed fitting portion (depressed engaging portion) 95 on the front outer periphery, having slits 94, 94, . . . , parallel to the axis, and mating the aforementioned projected fitting portion 72 of applicator body 70 in a detachable manner with an appropriate interface. A joint portion 96 which is reduced in outside diameter is formed at the rear of the depressed fitting portion so as to be fitted into applicator body 70.
Assembly of the thus constructed applicator body 70, cartridge tank 80 and tail plug 90 is started with tail plug 90 being fitted from the rear end side of cartridge tank 80. In this case, the front opening edge, designated at 97, of tail plug 90 abuts stepped portion 84 of cartridge tank 80, so that fitting of tail plug 90 stops. The tail plug 90 thus fitted is inserted into applicator body 70 from its rear end opening. Thereby, depressed fitting portion 95 of tail plug 90 is fitted and fixed to projected fitting portion 72 of applicator body 70 as the outer peripheral part, having slits 94, contracts narrowing the slits 94 within limit, while pipe 73 of applicator body 70 is inserted into the opening of inner front barrel 83 of cartridge tank 80. Thus, the assembly is completed.
With this conventional applicator 70 thus configured, the pressure in cartridge 80 decreases due to repeated liquid discharge, hence the liquid at the applying portion is drawn back into the cartridge, causing application failure. In some cases, the applicator may become unusable for sanitary reasons. Further, this kind of cartridge type applicator has a usable viscosity limit with respect to the application liquid, suffering problems with high viscosity liquids, through no problems occur with low viscosity liquids.